Name

       nix fmt - reformat your code in the standard style

Synopsis

       nix fmt [option…] args…

Examples

       With nixpkgs-fmt (https://github.com/nix-community/nixpkgs-fmt):

       # flake.nix
       {
         outputs = { nixpkgs, self }: {
           formatter.x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.nixpkgs-fmt;
         };
       }

       • Format the current flake: $ nix fmt

       • Format a specific folder or file: $ nix fmt ./folder ./file.nix

       With nixfmt (https://github.com/serokell/nixfmt):

       # flake.nix
       {
         outputs = { nixpkgs, self }: {
           formatter.x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.nixfmt;
         };
       }

       • Format specific files: $ nix fmt ./file1.nix ./file2.nix

       With Alejandra (https://github.com/kamadorueda/alejandra):

       # flake.nix
       {
         outputs = { nixpkgs, self }: {
           formatter.x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.alejandra;
         };
       }

       • Format the current flake: $ nix fmt

       • Format a specific folder or file: $ nix fmt ./folder ./file.nix

Description

       nix  fmt  will  rewrite  all  Nix  files (*.nix) to a canonical format using the formatter
       specified in your flake.

Options

       Common evaluation options:

       • --arg name expr
         Pass the value expr as the argument name to Nix functions.

       • --argstr name string
         Pass the string string as the argument name to Nix functions.

       • --eval-store store-url
         The Nix store to use for evaluations.

       • --impure
         Allow access to mutable paths and repositories.

       • --include / -I path
         Add path to the list of locations used to look up <...> file names.

       • --override-flake original-ref resolved-ref
         Override the flake registries, redirecting original-ref to resolved-ref.

       Common flake-related options:

       • --commit-lock-file
         Commit changes to the flake’s lock file.

       • --inputs-from flake-url
         Use the inputs of the specified flake as registry entries.

       • --no-registries
         Don’t allow lookups in the flake registries. This option is  deprecated;  use  --no-use-
         registries.

       • --no-update-lock-file
         Do not allow any updates to the flake’s lock file.

       • --no-write-lock-file
         Do not write the flake’s newly generated lock file.

       • --override-input input-path flake-url
         Override  a  specific  flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-
         file.

       • --recreate-lock-file
         Recreate the flake’s lock file from scratch.

       • --update-input input-path
         Update a specific flake input (ignoring its previous entry in the lock file).

       Options that change the interpretation of installables:

       • --derivation
         Operate on the store derivation rather than its outputs.

       • --expr expr
         Interpret installables as attribute paths relative to the Nix expression expr.

       • --file / -f file
         Interpret installables as attribute paths relative to the Nix expression stored in file.
         If file is the character -, then a Nix expression will be read from standard input.

                                                                                      nix3-fmt(1)